This invention relates to the formation of sealed packages, more particularly sealed packages containing a charge of a flowable product, for example a comminuted product, such as roasted and ground coffee, and formed from a sealable material.
Comminuted products, such as roasted and ground coffee, tea or instant coffee, are often sold in tins or in packages in the form or sealed bags made of a sealable plastics material. Such a sealable material may be heat sealable or pressure sensitive material (or a so-called cold seal material). The sealable material may include a barrier layer of aluminium foil. In some countries the product is generally packed in such sealed bags at atmospheric pressure; in others it is more usual for the product to be packed under vacuum so that the packaging material conforms closely to the product. This has the benefit that the product is protected from the effects of oxygen and the environment and also that the package, which typically has a rectangular parallelepipedal shape somewhat similar to a brick, takes up less space than a package that has been packed at atmospheric pressure.
Currently used technology involves placing the filled bags in turn into a bell chamber followed by evacuating the chamber and the bag before sealing the top of the bag within the bell chamber. This arrangement typically requires 12 seconds and 30 kW of pump power for bags containing 250 g to 1000 g (e.g. 500 g) of roast and ground coffee in order to evacuate the bags at a rate of 100 bags per minute. Hence the system is relatively slow and has high energy requirements.
Other flowable materials which can be mentioned include sugar, flour, potato crisps, rice grains or flakes, and the like and liquids such as paint and soup.
FR-A-2560857 teaches a machine for filling sealed coffee bags which has a turntable with a drive underneath. Chambers around the periphery of the turntable each contain a vertically supported filled coffee bag. Each chamber is connected to a tube partly under the turntable. A throttling valve arrangement is provided with a channel which ends at a vertical tube communicating with a vacuum pump and to the atmosphere. A valve member is rotated by a radial arm which has a head that is held by a spring against a cam track acting as the turntable rotates. Connection with vacuum and with the atmosphere is achieved by means of a control disc, having a ring of holes, and slots. This arrangement is said to prevent escape of coffee powder.
In U.S. Pat. No. 4,730,439 there is disclosed a method of formation of vacuum sealed packets. In this method open topped packets are formed and filled, whereupon a vacuum tube is inserted in the top of the packet and then the side walls are urged around the vacuum tube in order to cause a temporary vacuum in the packet while the side walls are sealed together below the vacuum tube.
Use of a vacuum packer is described in FR-A-2488215; this nearly seals the packages by welding along the top edge or a side as air is drawn out by a probe which is extracted before final sealing. Sealing is effected by moving the package across a fixed welding head. The probe can be progressively retracted after the beginning of evacuation and before the final closure welding.
In GB-A-1474838 there is described an apparatus for evacuating a fluid from an open-ended flexible, thermo-sealable bag which comprises a bag holding member arranged to be inserted into the open end of the bag and to fit snugly against the inner surfaces thereof. This member has a plurality of openings in it connected to a vacuum source. A probe with a passage connected to a vacuum source is supported by the member and can be extended into and retracted from the bag. Sealing is effected after the probe is withdrawn from the bag.
GB-A-1416101 teaches use of a suction pipe for sucking gas out of a container containing a pulverulent or granular material. This pipe has a free end with a plurality of apertures separated by elastically deformable tongues effective to close the free end of the pipe by mutual engagement.
U.S. Pat. No. 3,796,020 discloses a hand operated machine or evacuating and sealing a bag.
In U.S. Pat. No. 3,589,098 an arrangement of cams is used to move a bag-evacuating nozzle, to move a pressure bar for applying pressure to the bag, to vary the length of the heater period, and to control the length of the sealing period.
GB-A-1199580 shows use of a hollow needle to evacuate a bag; this needle is then withdrawn before sealing bars close to seal the bag and a knife severs the evacuated bag.
U.S. Pat. No. 2,634,562 and its divisional, U.S. Pat. No. 2,692,074 teach a hand operated machine in which packages are sealed except at an ear. The plies of the bag are held apart by applying vacuum to the outer. surfaces and provide an opening through which the package can be evacuated before it is finally sealed.
A bag evacuating and closing apparatus with two opposed jaws which encompass a top closure of a bag to be sealed and which have hollow spaces is taught in U.S. Pat. No. 5,097,648. A sealing rib protrudes from one face end of one of two frames which surround the jaws. This sealing rib is interrupted in a middle region of the frame part at which the closure fold protrudes between the jaws. Suction openings in this region allow the walls of the top closure to be pulled tightly against the frame parts, whereupon air is sucked out of the bag which is then sealed by the sealing jaws.
A method and apparatus for producing a vacuum package filled with granular material are described in EP-A-0626312. A package filled with granular product is compressed by applying pressure to the side walls of the package so that the granular product forms a compact whole. Then the compressed package is evacuated through a small suction opening by means of a vacuum element comprising a needle. Thereafter the package is sealed with the aid of a separate sealing strip, which is placed inside the bag before filling, by pressing a heated sealing jaw against the wall in the region of the sealing strip, the compressed granular material providing support during this step for the sealing strip.
EP-A-0634324 discloses an apparatus for filling with an inert gas the head space of a tub which is closed by a lid.
In EP-A-0685391 there is disclosed a machine for forming-filling packaging bags, with provision for evacuating the filled bags, in the form of a sealed or tight bell.
For the sake of appearance it is desirable that, when the flowable material is a comminuted material such as roasted and ground coffee, the sealed package shall have as regular a shape as possible, most usually in the shape of a rectangular parallelepiped. It is, however, difficult to achieve reliably a truly rectangular parallelepipedal shape. This is because the packaging material tends to crinkle as the air is drawn out of the package and as the packaging material conforms to the outside of the parallelepipedal brick of coffee or other comminuted product. In addition there is the problem that, if any of the comminuted product is disturbed significantly during the evacuation step, it can become displaced into the seal area and result in formation of a faulty seal. There is also a danger that the roasted and ground coffee or other comminuted product can get drawn into the vacuum system.
Prior art methods and apparatus for forming sealed evacuated packages of comminuted products such as coffee are relatively slow in operation. However, although higher speeds are theoretically possible by enlarging the machinery, the size of the resulting machines becomes unmanageable for machines capable of operating at speeds above about 150 bags per minute.
It would be desirable to provide an apparatus for forming evacuated packages of flowable products, such as comminuted products, which is capable of operating reliably at significantly higher operating speeds than the current practical limit of about 150 bags per minute.
Accordingly there is a need in the art for a novel method, and an apparatus for use of such a method, of evacuating and sealing packages using bags made of a sealable material and containing a charge of a flowable product, such as a comminuted product, which can be operated at significantly higher speeds than have been achievable heretofore. There is also a need for a high speed method and apparatus for forming evacuated sealed packages containing roasted and ground coffee or another comminuted material which reliably gives a package with a pleasing finish substantially free from disfiguring creases and other blemishes.
The invention seeks to provide an improved method, and an apparatus of readily manageable size for use of such a method, of evacuating and sealing packages using bags made of a sealable material and containing a charge of a flowable product, such as a comminuted product, which can be operated at significantly higher speeds and lower power than have been achievable heretofore. It further seeks to provide a high speed method and apparatus for forming such packages which reliably gives an evacuated and sealed package containing a comminuted product with a pleasing finish substantially free from disfiguring creases and other blemishes.
According to one aspect of the present invention there is provided a method of evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, comprising the steps of:
(i) positioning a bag containing a charge of a flowable product and formed from a sealable material with its open end around a vacuum probe member and with said member extending into the bag to a first position;
(ii) forming a temporary seal at the open end of the bag around the probe member;
(iii) evacuating the bag through the probe member so as to produce a first pressure in the bag;
(iv) causing relative movement of the bag and said probe member so that said probe member is retracted relative to the bag and extends into the bag to a second position;
(v) forming a permanent seal in the bag at the open end of the bag in a position between the charge and the probe member in said second position;
(vi) subsequent to step (ii) but prior to completion of step (v) maintaining a predetermined pressure in said probe member which is higher than said first pressure so that gas flows from said probe member into said bag; and
(vii) releasing the temporary seal to allow release of the bag following completion of the permanent seal.
In such a method it is preferred that said temporary seal is formed by pressing elements which overlap the extremity of the opposed surfaces at the open end of the bag, so that said elements press said opposed surfaces against each other and around the probe member and seal against each other beyond said extremity. The probe member may include a stationary part around which said temporary seal is formed, and a movable part which extends from said stationary part when the probe member is in said first position and is substantially retracted when the probe is in said second position.
The invention also envisages that, in a preferred method, said temporary seal forming step includes forming a further temporary seal at the open end of the bag around said probe member in said first position, said further temporary seal being positioned between the charge and the position of the permanent seal and being maintained until after completion of the permanent seal.
Particularly when the flowable material is a comminuted solid material a charge of which can retain a solid shade in an evacuated package, the temporary seal forming step preferably includes pressing jaw members against the bag, including the step of causing relative movement of the bag and said jaw members after said further temporary seal has been formed and prior to completion of the permanent seal, so as to cause the adjacent surface of the charge to be pressed into a desired shape by the bag material adjacent that held between said jaws.
The probe member may extend in said first position to a position closely adjacent the surface of said charge. It is further preferred that the pressure in said probe member is maintained at a reduced value up to completion of said permanent seal, whereby ambient pressure acting on the outer part of said bag in the region of said probe member in said second position assists in maintaining the bag sealed.
The invention further provides a method of evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, comprising the steps of:
(i) positioning a bag containing a charge of a flowable product and formed from a sealable material with its open end around a vacuum probe member and with said member extending into the bag to a first position;
(ii) forming outer and inner spaced temporary seals at the open end of the bag and around said probe member in said first position;
(iii) evacuating the bag through the probe member;
(iv) causing relative movement of the bag and said probe member so that said probe member is retracted relative to the bag and extends into the bag to a second position in which said member extends through said outer temporary seal but not through said inner temporary seal;
(v) forming a permanent seal in the bag at the open end of the bag at an intermediate region between said outer and inner temporary seals and between the charge and the probe member in said second position; and
(vi) releasing the outer and inner temporary seals to allow release of the bag following completion of the permanent seal.
Also provided in accordance with the invention is a method of evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, comprising the steps of:
(i) positioning a bag containing a charge of a flowable product and formed from a sealable material with its open end around a vacuum probe member and with said member extending into the bag to a first position;
(ii) forming an outer temporary seal at the open end of the bag around said probe member;
(iii) pressing jaw members against the bag so as to form an inner temporary seal at the open end of the bag around said probe member in said first position, said further temporary inner seal being positioned between the charge and the outer temporary seal and spaced from the outer temporary seal;
(iv) causing relative movement of the bag and the jaw members after said inner temporary seal has been formed so as to cause the adjacent surface of the charge to be pressed into a desired shape by impingement of the bag material adjacent that held between the jaw members against the jaw members;
(v) evacuating she bag through the probe member;
(vi) prior to or subsequent to completion of step (iv) causing relative movement of the bag and said probe member so that said probe member is retracted relative to the bag and extends into the bag to a second position while maintaining the outer and inner temporary seals; and
(vii) forming a permanent seal at the open end of the bag in a position between the inner and outer temporary seals and between the surface of the charge and the probe member in its second position.
The jaw members can in this last mentioned case have flat surfaces against which the adjacent surface of the charge is pressed by impingement of the bag material adjacent that held between the jaw members against the jaw members so as to assist in forming a squared sealed end to the sealed bag.
In yet another aspect of the invention there is provided a method of evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, the method comprising the steps of:
(A) positioning a bag containing a charge of a flowable product and formed from a sealable material with its open upper end around a substantially vertical sleeve of an evacuation and sealing head assembly, the evacuation and sealing head assembly further comprising a substantially vertically retractable vacuum probe for evacuating the upper end of the bag above the charge, the vacuum probe being movable between an extended position in which its lower end extends below a lower end of the sleeve and a retracted position, a pair of upper jaw members movable towards each other to a closed position in which portions of the upper jaw members grip an upper extremity of the bag against the sleeve to form an outer temporary seal and movable away from each other to an open position to release the upper extremity of the bag, a pair of lower jaw members below the upper jaw members and movable towards each other to a closed position in which portions of the lower jaw members grip a lower region of the bag against the vacuum probe in its extended position to form an inner temporary seal, the lower region being below the upper extremity of the bag and above the charge in the bag, and movable away from each other to an open position to release the lower region of the bag, and a pair of sealing members movable towards each other, following retraction of the vacuum probe to its retracted position, to a closed sealing position in which the sealing members contact the outside of an intermediate region of the upper end of the bag extending across the entire width of the bag below its upper extremity and above the lower region to form a seal extending across the intermediate region thereby to seal the bag so as to form a package and movable away from each other to an open position to release the sealed package;
(B) evacuating the bag through the vacuum probe with the vacuum probe extended to its extended position through the sleeve into the bag into the space above the charge, with the upper jaw members closed against the sleeve to grip the upper extremity of the bag against the sleeve and form an outer temporary seal, and with the lower jaw members closed to grip the lower region of the bag against the probe and form an inner temporary seal;
(C) retracting the vacuum probe from its extended position to its retracted position whilst maintaining reduced pressure in the vacuum probe;
(D) moving the sealing members to their closed positions to cause the sealing members to contact the outside of the intermediate region of the upper end of the bag to effect formation of a permanent seal and to form a package;
(E) retracting the sealing members while maintaining the upper and lower jaw members in their respective closed positions; and
(F) moving the upper and lower jaw members each to their respective open positions to release the now sealed package from the evacuation and sealing head assembly.
In contrast to the currently used commercial method which involves the use of a bell chamber, the method of the invention involves insertion of a hollow probe inside the bag so that essentially only air trapped in the bag requires to be removed. It has been found that evacuation can be achieved in approximately 3 seconds for a bag containing 500 g of roast and ground coffee under appropriate operating conditions. Moreover the pump power is considerably reduced compared with the prior art process, the power requirement for evacuating such bags at a rate of 300 bags per minute being between about 1 kW and about 2 kW.
The sealable material from which the bag is formed may comprise a pressure sensitive (or cold seal) material; in this case formation of a seal can be accomplished in step (D) by applying pressure alone during contact of the sealing members with the outside of the intermediate region of the upper end of the bag. Such pressure sensitive materials are well known to those skilled in the art. Alternatively, and more usually, the sealable material may comprise a heat sealable material. Normally the sealable material will comprise a laminate sheet material including a sealable layer and the bag is formed so that the layer of sealable material is on the inside of the bag.
When using a heat sealable material the sealable material will normally be chosen so as to have a softening point, at which it can bond to a similar softened layer, that is lower than the melting point of the other layer or layers of the bag. In this case formation of a seal in step (D) can be accomplished by supplying heat to the sealing members by means of internal electrical heating elements so as to maintain the sealing members at a temperature above the softening point of the sealable layer but below the melting point of any other layer of the laminate and by pressing the heated sealing members into contact with the outside of the intermediate region of the upper end of the bag with a pressure and for a time sufficient to cause formation of a heat seal thereby to form a package. This time will depend upon such factors as the thickness and thermal conductivity of the heat sealable material and is sufficiently long to soften the internal surfaces of the bag in the seal area enough to form a seal but not so long as to melt any other layer of the heat sealable material. As an example of a suitable heat sealable material there can be mentioned a laminate of reverse printed polyethylene terephthalate, low density polyethylene and peelable low density polyethylene. Such a laminate can be, for example, from about 75 xcexcm to about 150 xcexcm thick, e.g. about 100 xcexcm thick. Other heat sealable materials available in web form are well known to those skilled in the art, including laminate materials including a thin metallic layer.
In a particularly preferred form the bag has a rectangular base, a pair of opposed longer walls, which form a front wall and a back wall to the bag, and a pair of shorter side walls. In this case the completed package has essentially the shape of a rectangular parallelepiped.
Conveniently the bag is formed from a web of heat sealable sheet material which is first formed into a tube with a longitudinal seal, conveniently a longitudinal fin seal, by sealing together longitudinal edge portions of the web. In addition to the longitudinal seal the bag also has a transverse bottom fin seal; when the bag is to form a substantially parallelepipedal package the bottom fin seal may be gusseted. The individual bag lengths are severed from the web after formation of the longitudinal fin seal and prior to filling.
In the method of the invention the bag is preferably supported in an open topped container whose internal dimensions correspond generally to the outside dimensions and cross section of the package. Preferably the bag is inserted into such an open topped container prior to filling with the charge of comminuted or other flowable material. The bag may in this case be inserted in flat form into the open topped container and opened out, prior to filling, while it is in the open topped container. Preferably the bag, after filling with a charge of comminuted or other flowable material, is subjected to vibration or tamping, or both, in order to compact the comminuted or other flowable material prior to evacuation and sealing and to assist in importing a smooth top surface to the charge in the bag.
When the package is to have a substantially parallelepipedal shape, the open topped container is also substantially parallelepipedal and accordingly encloses the bag on five sides leaving only the top surface open.
In the method of the invention it is preferred that, in step (A), the upper jaw members are initially in their open position and that the upper jaw members commence to move towards their closed position prior to initiation of step (B). Preferably the upper jaw members reach their closed position prior to commencement of evacuation.
The upper jaw members are preferably provided with resilient pads on their mutually inner faces. Typically such resilient pads measure about 20 mm to about 30 mm (e.g. about 25 mm) from top to bottom of their mutually contacting surfaces. In step (A), the bag is preferably, positioned so that its upper rim lies a little below, e.g. from about 10 mm to about 15 mm below, e.g. about 12.5 mm below, the top of the resilient pads on the upper jaw members. Thus, when the upper jaw members close to form an upper temporary seal, the upper portions of the resilient pads contact one another and the outside of the sleeve and provide an air-tight seal above the upper rim of the bag prior to commencement of evacuation.
When the package is to have a substantially parallelepipedal shape, the evacuation and sealing head assembly may further include a pair of gusset-forming members movable, in a direction substantially at right angles to the direction of movement of the upper jaw members, between an open position and a closed position in which the gusset-forming members contact the outside surfaces of the bag and form gussets in the bag; in the method of the invention the gusset-forming members are preferably initially in their open position and move towards their closed position as the upper jaw members move towards their closed position, and then the gusset-forming members are moved to their open position before the commencement of step (D). It is convenient if the gusset-forming members are mounted on pivotally mounted arms for arcuate movement about a substantially vertical axis between their open and closed positions. Such gusset-forming members are arranged to form gussets near the top end of the bag just below the intermediate region where the seal is to be formed.
In step (A) the bag is preferably so positioned vertically with respect to the lower end of the sleeve that the upper surface of the charge of flowable product in the bag lies at a first distance below the lower end of the sleeve corresponding to a position in which the upper surface or the charge of comminuted or other flowable product in the bag also lies below the lower end of the hollow probe in its extended position and, prior to commencement of step (B), the bag is raised to a raised position in which the upper surface of the charge of comminuted or other flowable product in the bag lies at a second distance below the lower end of the sleeve, the raised position being a position such that, when the hollow probe is moved to its extended position, the upper surface of the charge in the bag is in close proximity to the lower end of the hollow probe. Preferably in the raised position of the open topped container the upper surface of the charge of comminuted or other flowable product in the bag lies at a second distance below the bottom of the sleeve corresponding to a third distance of less than about 1 cm below, for example less than about 1 mm to about 2 mm below, the lower end of the hollow probe in its extended position. Preferably in the raised position of the bag the upper surface of the charge of comminuted or other flowable product in the bag will just contact the lower end of the hollow probe in its extended position. Furthermore, particularly when the flowable material is a comminuted product such as roasted and ground coffee, the lower jaw members are preferably so designed that, in its raised position and with the lower jaw members closed, the upper surface of the charge of comminuted or other flowable material in the bag presses the material of the bag against the underside of the lower jaw members. In this way the coffee or other comminuted product is prevented from lifting due to efflux of air as the vacuum is applied to the inside of the bag and, in addition, the appearance and squareness of the top of the bag are improved.
In step (A) the lower jaw members are preferably initially in their open position and are moved to their closed position prior to commencement of step (B). It is further preferred that the lower jaw members reach their closed position after the upper jaw members reach their closed position and even more preferred that they reach this closed position before evacuation commences. The lower jaw members may be provided on their mutually facing surfaces with resilient pads which engage the lower region of the bag in their closed position and resiliently press the inner surfaces of the lower region of the bag against the hollow probe to form an inner temporary seal, while permitting withdrawal of the probe from its extended position to its retracted position prior to commencement of step (D).
It will usually be preferred for the hollow probe to be moved from its retracted position to its extended position prior to the lower jaw members reaching their closed position.
The end of the hollow probe is preferably provided with a protective filter, gauze or perforated sheet to hinder passage of particles of comminuted or other flowable product up the interior of the hollow probe and in step (B) vacuum is preferably applied through the hollow probe for a period sufficient to reduce the pressure inside the bag to a first reduced pressure and then a predetermined small quantity of a medium selected from air, carbon dioxide, nitrogen, desirable aromas, and mixtures thereof is introduced into the bag thereby to dislodge particles of comminuted or other flowable product from the filter, gauze or perforated sheet back into the bag and raise the pressure somewhat to a second reduced pressure. Besides helping to keep the end of the hollow probe clean, this variation of the method of the invention can be used to impart desirable characteristics to the sealed package, including the ability to release a desirable enhanced aroma of, for example, roasted and ground coffee when the package contains roasted and ground coffee. Thus, for example, if a small amount of a desirable aroma fraction is introduced in this way into the bag the second pressure may be less than about 200 millibars absolute, and preferably less than about 100 millibars absolute. In this case the resulting package is still a vacuum package. On the other hand, if the desired package is a soft, gas-flushed package, then sufficient inert gas (e.g. CO2 or N2 or a mixture thereof) can be bled back into the bag in this way so as to result in a second pressure of at least 800 millibars absolute up to atmospheric pressure, or even a few millibars above (e.g. from about 5 to about 30 millibars above) atmospheric pressure. In this way the contents of the package can be maintained in an inert gas atmosphere and are protected from any deleterious effects of air (e.g. oxidation by O2).
The evacuation and sealing head assembly may be used as a stand alone item of equipment. Alternatively it may be mounted on a rotatable carousel arranged for rotation about a substantially vertical axis and provided with a plurality of stationary cam tracks; movement of the upper jaw members, of the lower jaw members, and of the sealing members between their respective open and closed positions is in this case effected by means of cam followers cooperating with the stationary cam tracks and connected to respective operating rods. Typically a plurality of evacuation and sealing head assemblies, for example, at least 30 evacuation and sealing head assemblies are mounted on the carousel. Yet again it is possible for a plurality of evacuation and sealing head assemblies to be mounted on a conveyor system and conveyed along a path of any desired shape, e.g. an oval path. The various steps of the method of the invention including opening and closing of the upper jaw members, of the lower jaw members and of the sealing members, as well as extension and retraction of the probe and operation of a valve or valves controlling the evacuation step, can be accomplished using pneumatic cylinders. Alternatively, when the evacuation and sealing head assembly is mounted on a carousel or on a moving conveyor, the appropriate movements can be achieved by means of push rods provided with cam followers acting upon appropriate cam tracks mounted on one or both sides of the path of movement of the evacuation and sealing head assembly. When cam tracks are arranged on one side only of the path of movement of the evacuation and sealing head assembly opening and closing movement of the upper jaw members, the sealing members and/or the lower jaw members can be achieved by connecting one of the respective members to an operating rod carrying the respective cam follower and provided with a rack and the other of the respective members to another rod also provided with a rack and arranged to cooperate with a pinion in engagement with the rack on the respective operating rod.
If the evacuation and sealing assembly further includes a pair of gusset-forming members, then they can be arranged so that movement of the gusset-forming members between their open and closed positions is effected by means of a corresponding cam follower cooperating with a stationary cam track and connected to a respective main operating rod.
In one arrangement the gusset-forming members are mounted on respective pivotally mounted arms each fixed to a respective vertical axle for arcuate movement about a substantially vertical axis between their open and closed positions, the vertical axles each further carrying a respective pinion, and the respective operating rod is provided with a pair of rack portions each of which cooperates with a corresponding pinion on one of the vertical axles.
In addition it can be arranged so that one of the upper jaw members is connected to its respective main operating rod, while the other upper jaw is attached to a pair of subsidiary operating rods and the vertical axles each carry a further loose pinion which cooperates with a respective rack portion on the main operating rod for the upper jaw members and with rack portions on those subsidiary operating rods, whereby movement of the main operating rod for the upper jaw members in one direction causes the upper jaw members to move towards their closed position and movement of that main operating rod in the opposite direction causes the upper jaw members to move towards their open position.
Also one of the lower jaw members can be connected to its respective main operating rod, while the other lower jaw is attached to a pair of subsidiary operating rods and the vertical axles each carry a further loose pinion which cooperates with a respective rack portion on the main operating rod for the lower jaw members and with rack portions on those subsidiary operating rods, whereby movement of the main operating rod for the lower jaw members in one direction causes the lower jaw members to move towards their closed position and movement of that main operating rod in the opposite direction causes the lower jaw members to move towards their open position.
Furthermore one of the sealing members can be connected to its respective main operating rod, while the other sealing member is attached to a pair of subsidiary operating rods and the vertical axles each carry a further loose pinion which cooperates with a respective rack portion on the main operating rod for the sealing members and with rack portions on those subsidiary operating rods, whereby movement of the main operating rod for the sealing members in one direction causes the sealing members to move towards their closed position and movement of that main operating rod in the opposite direction causes the sealing members to move towards their open position.
Another preferred feature of the invention is that the bag is supported in an open topped container and the open topped container is provided with a cam follower which cooperates with a respective cam track to cause vertical movement of the open topped container and bag as required during the operating cycle. The open topped container is preferably moved by a conveyor in synchronism with the carousel.
The invention further provides apparatus for evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package comprising:
an evacuation and sealing head assembly comprising:
a substantially vertical sleeve around which an open upper end portion of a bag can be positioned, the bag containing a charge of a flowable product and formed from a sealable material;
a substantially vertically retractable vacuum probe movable between an extended position in which its lower end extends below a lower end of the sleeve and a retracted position;
means or moving the probe between its extended and retracted positions;
a pair of upper jaw members movable towards each other to a closed position in which portions of the upper jaw members can grip an upper extremity of the bag against the sleeve to form an outer temporary seal and movable away from each other to an open position to release the upper extremity of the bag;
means for moving the upper jaw members between their closed and open positions;
a pair of lower jaw members below the upper jaw members and movable towards each other to a closed position in which portions of the lower jaw members grip a lower region of the bag against the vacuum probe in its extended position to form an inner temporary seal, the lower region being below the upper extremity of the bag and above the charge in the bag, and movable away from each other to an open position to release the lower region of the bag;
means for moving the lower jaw members between their closed and open positions;
a pair of sealing members movable towards each other, following retraction of the vacuum probe to its retracted position, to a closed sealing position in which the sealing members contact the outside of an intermediate region of the upper end of the bag extending across the entire width of the bag below its upper extremity and above the lower region to form a permanent seal extending across the intermediate region thereby to seal the bag so as to form a package and movable away from each other to an open position to release the sealed package; and
means for moving the sealing members between their closed and open positions; and
vacuum means for evacuating the bag through the vacuum probe with the vacuum probe extended to its extended position through the sleeve into the bag into the space above the charge and with the upper jaw members closed against the sleeve to grip the upper extremity of the bag against the sleeve thereby to form an outer temporary seal.
In such an apparatus the upper jaw members can be arranged so that they commence to move towards their closed position prior to actuation of the vacuum means to cause evacuation of the bag.
In a preferred form of apparatus of the invention the evacuation and sealing head assembly further includes a pair of guesset-forming members movable in a direction substantially at right angles to the direction of movement of the upper jaw members between an open position and a closed position in which the gusset-forming members contact the outside surfaces of the bag and form gussets in the bag, the gusset-forming members being arranged to move from their open position and towards their closed position as the upper jaw members move towards their closed position, and the gusset-forming members being arranged to move to their open position before inward movement of the sealing members to their closed position to form a permanent seal to the bag.
In such an apparatus the gusset-forming members can be mounted on pivotally mounted arms each for arcuate movement about a substantially vertical axis between their open and closed positions.
The apparatus preferably includes an open topped container for support of the bag which is movable to a vertical position in which the upper surface of the charge of comminuted or other flowable product in the bag lies at a first distance below the lower end of the sleeve corresponding to a position in which the upper surface of the charge of flowable product in the bag lies below the lower end of the hollow probe in its extended position and also to a raised position in which the upper surface of the charge of flowable product in the bag lies at a second distance below the lower end of the sleeve, the raised position being a position such that, when the hollow probe is moved to its extended position, the upper surface of this charge in the bag is in close proximity to the lower end of the hollow probe.
In the apparatus according to the invention the lower jaw members are arranged to be moved to their closed position prior to the sealing members being moved to their closed position. The lower jaw members can reach their closed position at the same time as, or after the upper jaw members reach their closed position.
It is desirable for the lower jaw members to be provided on their mutually facing surfaces with resilient pads which engage the lower region of the bag in their closed position and resiliently press the inner surfaces of the lower region of the bag against the hollow probe to form an inner temporary seal, while permitting withdrawal of the probe from its extended position to its retracted position prior to the sealing members reaching their closed position.
The hollow probe is preferably arranged to move from its retracted position to its extended position prior to the lower jaw members reaching their closed position.
In another of its aspects the invention provides apparatus for evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, comprising:
(i) a vacuum probe member for evacuation of a bag whose open end is positioned around the probe member, which contains a charge of a flowable material and which is formed from a sealable material, said probe member comprising a part which is movable relative to the bag between a first position in which said part extends through the open end of the bag into the bag and a second position in which the part is retracted relative to the bag but still extends into the bag;
(ii) vacuum connection means for connection of the vacuum probe to a vacuum pump means for evacuation to a first pressure of a bag positioned with its open end around the probe member, said vacuum connection means including a valve means allowing in an open condition of the valve means connection between the interior of the bag and the vacuum pump means and in a closed condition of he valve means causing isolation of the bag when at said first pressure from the vacuum pump means;
(ii) means for opening and closing said valve means;
(iv) means for effecting relative movement of the part between its first and second positions;
(v) means for forming a temporary seal at the one end of the bag around the probe member;
(vi) means for admitting a predetermined quantity of a compressible fluid to said probe member so that, when the valve means is in its closed condition with a bag around the probe member at the first pressure, a second pressure higher than the first pressure is thereby produced in said probe member and in the bag; and
(vii) means for forming a permanent seal in the bag at the open end of the bag in a position between the charge and the probe member in said second position.
In such an apparatus said means for forming said temporary seal may comprise elements relatively movable towards and away from each other between open and closed positions which overlap in their closed positions the extremity of the opposed surfaces at the open end of the bag, so that said elements press said opposed surfaces against each other and around the probe member and seal against each other beyond said extremity. Furthermore the probe member can include a stationary part around which said temporary seal is formed, and a movable part which extends from said stationary part when the probe member is in said first position and is substantially retracted when the probe is in said second position. In addition the apparatus may include means for forming a further temporary seal at the open end of the bag around said probe member between the charge and the position of the permanent seal, said further temporary seal forming means being arranged so that said further temporary seal can be maintained until after completion of the permanent seal. Said means for forming said further temporary seal conveniently includes jaw members relatively movable towards and away from each other between open and closed positions and movable to their closed positions, after said further temporary seal has been formed and prior to completion of the permanent seal, so as to press against the bag in their closed positions and to cause the adjacent surface of the charge to be pressed into a desired shape by the bag material adjacent that held between said jaw members. It will normally be preferred in an apparatus in accordance with this aspect of the invention for the probe member to be arranged to extend in said first position to a position closely adjacent the surface of said charge. Moreover said valve means is preferably arranged so as to be maintained in closed condition so as to maintain the pressure in said probe member at a reduced value up to completion of said permanent seal, whereby ambient pressure acting on the outer part of said bag in the region of said probe member in said second position assists in maintaining the bag sealed.
The means for admitting a predetermined quantity of a compressible fluid to said probe member preferably comprises a valve means arranged for connection to a source of the compressible fluid, e.g. atmospheric air, an inert gas such as N2, CO2, or a mixture thereof, or a source of a desirable aroma fraction; this valve means is accordingly preferably provided with a valve member permitting, in one position of the valve member communication between the source of compressible fluid and an intermediate chamber and, in another position of the valve member, communication between the intermediate chamber and the interior of the probe member. In another aspect of the invention apparatus for evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, comprises:
(i) a vacuum probe member for evacuation of a bag whose open end is positioned around the probe member, which contains a charge of a flowable material and which is formed from a sealable material;
(ii) means for forming outer and inner spaced temporary seals at the open end of the bag and around said probe member in said first position;
(iii) means for evacuating the bag through the probe member;
(iv) means for causing relative movement of the bag and said probe member so that said probe member is retracted relative to the bag and extends into the bag to a second position in which said member extends through said outer temporary seal but not through said inner temporary seal; and
(v) means for forming a permanent seal in the bag at the open end of the bag at an intermediate region between said outer and inner temporary seals and between the charge and the probe member in said second position;
said apparatus being arranged whereby upon releasing the outer and inner temporary seals the bag is released following completion of the permanent seal.
In a still further aspect of the present invention there is provided apparatus for evacuating and sealing a bag containing a charge of a flowable product and formed from a sealable material so as to form a sealed package, comprising:
(i) a vacuum probe member for evacuation of a bag whose open end is positioned around the probe member, which contains a charge of a flowable material and which is formed from a sealable material, said probe member comprising a part which is movable relative to the bag between a first position in which said part extends through the open end of the bag into the bag and a second position in which the part is retracted relative to the bag but still extends into the bag;
(ii) means for forming an outer temporary seal at the open end of the bag around said probe member;
(iii) jaw members relatively movable between open and closed positions and arranged so that in their closed positions they press against the bag so as to form an inner temporary seal at the open end of the bag around said probe member in said first position, said further temporary inner seal being positioned between the charge and the outer temporary seal and spaced from the outer temporary seal;
(iv) means or causing relative movement of the bag and the jaw members after said inner temporary seal has been formed so as to cause the adjacent surface of the charge to be pressed into a desired shape by impingement of the bag material adjacent that held between the jaw members against the jaw members;
(v) means for evacuating the bag through the probe member;
(vi) means for causing relative movement of the bag and said probe member so that said probe member is retracted relative to the bag and extends into the bag to a second position while maintaining the outer and inner temporary seals; and
(vii) means for forming a permanent seal at the open end of the bag in a position between the inner and outer temporary seals and between the surface of the charge and the probe member in its second position.
In this case the jaw members can have flat surfaces against which the adjacent surface of the charge is pressed by impingement of the bag material adjacent that held between the jaw members against the jaw members so as to assist in forming a squared sealed end to the sealed bag.